Limuli plays a vital role in the ecology of estuarine and coastal communities. Horseshoe crabs utilize autochthonous and allochthonous production from pelagic and benthic food webs(figure 2; Carmichael et al. 2004). The horseshoe crab is an integral part of many vertebrate predators diet. Benthic fish feed on horseshoe crab eggs and larvae, sharks feed on the smaller juveniles, and sea turtles feed on adults (Botton et al. 2003). Horseshoe crabs are dietary generalists, and adult crabs are ecologically essential bivalve predators in some locations. One of the most notable predator-prey relationships that were pointed out to us while we were at the Georgia Aquarium was the migratory shorebird–horseshoe crab egg interaction. Eleven species, such as the more familiar red knot(featured to the right) and the dowitcher, rely on horseshoe crab eggs for sustenance during their migration along the Atlantic Flyway (Castro and Myers 1993). Migrating birds require an estimated 539 metric tons of eggs to full the trip to the Arctic summer range(Castro and Myers 1993). To bring this into better perspective let's consider the aforementioned red knot species.The red knot species depends so heavily on the abundance of horseshoe crab eggs that with this species depletion this bird over the last 20 years has seen a population decline from over 100,000 to less than 15,000. Thus, the red knot is now a species nominated for protection under the Endangered Species Act. Horseshoe crabs are therefore a critical species. The horseshoe crab links an array of prey (bivalves and polychaete worms) and predators (fish, turtles, and birds), utilizing both autochthonous and allochthonous production from pelagic and benthic food webs(figure 2; Carmichael et al. 2004).